As a clergy person, I get two particular questions a lot (and they are variations of the same concern):
1. Why must we pray for good things; doesn't God know what we need and can't God just provide for those needs without being asked?
2. Why are some prayers answered and others aren't?
Both questions suggest an ancient, theistic understanding of divinity. The questions imply that there are gods on a far away mountain or in a sky realm hidden by clouds and they favor some mortals over others, or they are largely indifferent but can be cajoled into offering assistance. And if that is our understanding of divinity, then of course we become frustrated, even angry. Why should the gods grant me a convenient parking place but not protect my car from a runaway shopping cart? Why should the deities bring good fortune into my life only later to let it slip away?Why should the fates add a blessing to one person's medical treatment and not another's? The god in the sky or on the mountain top is notoriously unreliable and often quite unfair.
But here is the good news...there are other ways of understanding "God." God is the word we have inherited for Ultimate Reality, Eternity, the Infinite, the Field of All Possibilities, the Life-force within us. Some prefer to call this "Something" a Higher Power, others see life as being filled with so many seemingly random occurrences that belief in God is problematic. Still others see God as the spirit of life, an omnipresent Reality, an indwelling and all-embracing energy, a web of existence connecting all life. We are not limited to the super-human personalities of Asgard or Olympus any longer. Even Jesus said, "God is spirit..." which we could understand as energy, the breath of life, a ubiquitous gestalt. With that understanding of God, we can say as Jesus did, "the divine and I are one!"
If we say "God" but think of a Zeus or Odin type of character with human personality, then like all other human personalities, that God will eventually disappoint us. But, if God (to borrow from the poet Epimenides and the "Acts of the Apostles") is that in which "we live and move and have our being," then God isn't separate from us, granting some wishes and ignoring others; rather, God is a power within and all around us that we can tap into to help us make the most of the opportunities and possibilities in life.
Apparent delays and denials may not be the action (or annoying inaction) of Apollo, Isis, or Lakshmi; they may simply suggest that we have not yet learned how to do better, or we have not yet healed mental blocks that are in the way of some achievement, or that our desired good is in the works and just hasn't shown up for us yet.
Some of the great spiritual teachers have reminded us that what God does for us, God must do through us. That makes God a partner, something with which we can cooperate (like gravity or electricity), something we can explore and express more of as our journey unfolds. Perhaps the "why hasn't God fixed it yet" questions suggest a need for a new understanding of God, and empowered by a new understanding, we may yet find more peace, hope, and even achievement going forward.